vice president joe biden and paul ryan prepare to square off tonight in kentucky. new poll numbers show the current vp has his work cut out for him. according to a new survey from the pugh center, 39% of registered voters view biden favorably. that's compared to 44% who favor ryan. when it comes to predicting the winner of tonight's debate, 40% of registered voters say ryan will come out on top. 34% think biden will prevail. nbc's tracie potts has a preview of tonight's debate. good morning. >> reporter: good morning. the pressure is on vice president biden to try to turn things around after the presidential debate last week. he has the experience on the debate stage to do so. but as you saw in the numbers, it looks like the public is betting more on paul ryan. ryan took a bit of an exertion yesterday while he was practicing in florida saying that the vice president will probably come at me like a cannonball. but that the obama record, as ryan put it, is his achilles heel. ryan is in kentucky after debate preps in florida and virginia. he's done three mock debates.